Module to Control a Rotating Output Shaft and a Module to Change a Driving Condition of Vehicle

ABSTRACT

A sensor and a control circuit are provided externally of a gear cover. This enhances reliability of a shift controller operated by an electric actuator and a motor driven control module similar thereto, and constitute them compact. Further, this provides a rotating position detection sensor suitably used for a switching device as described. A circuit and a sensor are not contaminated with oil or metal powder of a gear mechanism portion.

RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.11/132,178, which issued as U.S. Pat. No. 7,215,115 on May 8, 2007,which is a continuation of U.S. application Ser. No. 10/325,883, whichissued as U.S. Pat. No. 6,931,957, which claims the benefit of priorityunder 35 U.S.C. §119 to Japanese Patent Application No. 2001-388685filed Dec. 21, 2001, the disclosure of which is incorporated byreference herein.

BACKGROUND OF THE INVENTION

The present invention relates to a shift controller in a wide sense forswitching two-wheel drive/four-wheel drive of a motor vehicle or forswitching a transmission channel of the drive force as in atransmission, and particularly to a shift controller to be operated byan electric actuator. Further, it can be utilized also for a motor drivetype control module similar to the former. Moreover, this is relatedalso to a rotating position detection sensor used for such a switchingdevice as described.

In conventional devices, a shift controller described in U.S. Pat. No.6,155,126 has a gear arranged capable of transmitting torque between amotor and a shift rail as an output member, and comprises a housing forreceiving a motor and a gear mechanism, and a cover, wherein a controlcircuit board including a microcomputer is mounted on the inner surfaceof the cover, and the control circuit board is formed with a pluralityof rotation detectors and its processing circuit.

Further, there has been known, as described in Japanese Patent Laid-OpenNo. 94512/1999, an angle sensor in which a magnet is mounted on arotational body, and a change in magnetic field of a magnet depending onthe position of the rotation angle is measured by a magnetic sensorelement, the sensor comprising a measuring element for determining adirection signal depending on the direction of magnetic field crossingthe measuring element, and an evaluation circuit for determining anangle position from an output signal of the magnetic sensor element andan output signal of the direction measuring element.

Further, there has been known a method for computing an angle using athreshold calculated by a pre-stored reference table and calibration asdescribed in SAE2001-01-0984 as a processing technique of a rotatingposition signal.

The aforementioned conventional techniques pose a problem that since thecontrol-circuit board is exposed into the gear receiving chamber, thecontrol circuit is erroneously operated due to dust, oil and iron powdergenerated in the gear receiving chamber.

The aforementioned conventional techniques pose a problem that since therotational body and the rotation angle sensor or the signal processingcircuit of the sensor are exposed to the gear receiving chamber, therotation angle sensor or the signal processing circuit is erroneouslyoperated due to dust, oil and iron powder generated in the rotationalbody.

In the aforementioned conventional techniques, to detect a rotationangle over 360 degrees of an output rotating shaft, a first sensormechanism for detecting a rotational direction and a rotation angle of amotor, and a second sensor mechanism for detecting an angle position ofthe output rotating shaft are necessary, and the sensor mechanisms werecomplicated. Further, there poses a problem that the resolution of thesenor is affected by a gear ratio.

The aforementioned conventional techniques pose a problem that since asensor output signal is a pulse, only the dispersal angle detection canbe done.

The aforementioned conventional techniques pose a problem that since aHole element is used, it is necessary to keep the distance between arotational body and a sensor element within 3 mm, thus posing a problemthat management of distance between the hole element and the rotationalbody is severe.

In the aforementioned conventional techniques, a magnet is mounteddirectly on a rotational body, and to excite an angle sensor, it isnecessary to increase the magnetic force of a magnet or to make thedistance between the magnet and the sensor narrow, thus posing a problemwith cost of the magnet and assembling property.

In the aforementioned conventional techniques, to secure thetransmission mechanism, it is necessary to apply counterbore millingprocessing to the cover on which a gear cover and a board are mounted.Because of this, there poses a problem that the shape of the controlcircuit board is subjected to restriction conditions.

In the aforementioned conventional techniques, a gear is constitutedmerely by a spur gear, and when a motor is installed or at the time ofbacklash, an excessively large load is applied to the gear, thus posinga problem that the gear is broken.

In the aforementioned conventional techniques, since a motor and acontrol circuit board are connected through a conductor, there poses aproblem that when an excessive tensile stress is exerted between themotor and the control circuit board, the conductor is broken. Further,workability of the connection work was poor.

In the aforementioned conventional techniques, radiation of the controlcircuit board is not taken into consideration, thus posing a problemthat heat generated in the control circuit board is not radiated fromthe control circuit board, and at high temperature, the control circuitis erroneously operated.

In the aforementioned conventional techniques, a circuit board receivingcase (hereinafter called a board case) constituted from a housing and acover is of a closed construction, thus posing a problem that when theboard case is contracted or expanded, excessive stress is applied to thecontrol circuit board or the board case, and the control circuit boardor the board case is broken.

In the aforementioned conventional techniques, a positional relationbetween the rotational center axis of the magnet and the sensor isdeviated, and a change in magnetic flux crossing the sensor is not apoint symmetry, posing a problem that a sensor output is different everyproduct.

In the aforementioned conventional techniques, there poses a problemthat the sensor output is affected by the peripheral temperature of thesensor, and accordingly, the resolution is deteriorated due to thechange in temperature.

In the aforementioned conventional techniques, there poses a problemthat where an angle is measured over 360 degrees, since a first Holeelement and a second Hole element are necessary in addition to an MRsensor, the sensor mechanism is complicated.

In the aforementioned conventional techniques, there poses a problemthat in order to keep the distance between centers of the gears, a gearcase (housing) and a board case (cover) are provided with counterbores,and the distance between the gears is varied due to the assemblingtolerance or processing tolerance.

SUMMARY OF THE INVENTION

To achieve the object of the present invention, the constitution of thepresent invention is as follows:

<1>

In a module comprising a motor for driving a shift rail of a transfercase, a control circuit of said motor, and a gear mechanism fortransmitting rotation of said motor to said shift rail, the controldevice changes the driving condition of a vehicle in which the gearmechanism is enclosed by a cover attached externally.

<2>

In a module to change a driving condition of a vehicle, the module has ashift module comprising a shift rail of a transfer case driven by amotor vehicle, a gear mechanism for transmitting rotation of the motorto the shift rail, a non-contact type magnetic sensor for detecting arotating position of said shift rail, wherein the magnetic sensorcomprises a magnet rotated together with the shift rail, and a GMRelement for measuring the magnetic field which changes according to therotating position of the magnet, and the GMR element is attached at aposition facing to the magnet, externally of a cover for enclosing thegear mechanism.

<3>

In the module to change a driving condition of a vehicle according toitem 2, the cover also serves as a board on which the control circuit ismounted, and the GMR element is mounted on the board together with thecontrol circuit.

<4>

In the module to change a driving condition of a vehicle according toitem 2, the magnetometric sensor detects a rotating position of 360degrees of the shift rail.

<5>

A module to change a driving condition of a vehicle comprising a motorfor driving a shift rail of a transfer case, a gear mechanism fortransmitting rotation of the motor to the shift rail, a metal case forreceiving the motor and the gear mechanism, and a resin cover forcovering the motor and the gear mechanism covered by the metal case.

<6>

In the module to change a driving condition of a vehicle according toitem 5, a control circuit board for driving the motor is attachedexternally of the resin cover, and the motor is electrically connectedto the control circuit by electric wiring which extends through theresin cover.

<7>

In a module for transmitting the turning force from a rotating shaft ofa motor to an output rotating shaft through a reduction gear, the outputrotating shaft and the rotating shaft of a motor are arranged in amutually crossing positional relation. There is provided a housingformed with a recess for receiving the gear mechanism including theoutput rotating shaft and the motor laterally arranged. The controldevice comprises a cover member for forming a chamber for receiving thegear mechanism including the output rotating shaft and the motorlaterally arranged in cooperation with the recess mounted in the housingand formed in the housing, and a control circuit portion of the motor ismounted externally of the cover member. An electric conductor portionmade of conductive rigid body which is bended into an L-shape isprovided between a power feed terminal of the motor and a connectionterminal of the control circuit portion.

<8>

In the module according to item 7, the electric conductor portion madeof conductive rigid body which is bended into an L-shape is formed on afeed terminal of the motor.

<9>

In the module according to item 7, the electric conductor portion madeof conductive rigid body which is bended into an L-shape is formed on anintermediate terminal mounted between the feed terminal of the motor andthe connection terminal of the control circuit portion.

<10>

In the module according to item 7, the electric conductor portion madeof conductive rigid body which is bended into an L-shape is formed fromthe feed terminal of the motor and the connection terminal of thecontrol circuit portion.

<11>

A module to control a position of an output rotating shaft comprises: amotor for drivingly rotating an output rotating shaft to a fixedposition through a gear mechanism; a control circuit of the motor; ahousing for holding the output rotating shaft and the rotating shaft ofthe motor in such a manner that both of them are perpendicular to eachother; an intermediate gear mechanism provided between a gear formed ona rotating shaft end of the motor and a gear formed on the outputrotating shaft to transmit torque of the motor to the output rotatingshaft; a cover member defining a space for receiving an extreme end ofthe output rotating shaft, the intermediate gear and the motor incooperation with the housing; a magnet mounted on the extreme end of theoutput rotating shaft; a magnetic sensor element mounted at a positionfacing to the magnet externally of the cover member; the control circuitincluding a processing circuit for processing an output signal from themagnetic sensor element to detect a rotating position of the outputrotating shaft, electrically connected to the motor by an electricconductor extending through the cover member, and arranged externally ofthe cover member; and a connector portion formed on the cover member toreceive a desired position signal of the output rotating shaft in thecontrol circuit.

<12>

In a non-contact rotation sensor for detecting a rotating position of arotating shaft, a cover member made of resin for enclosing an end of therotating shaft is provided, a magnet is mounted on the end of therotating shaft, and a magnetic sensor element is mounted at a positionfacing to the magnet externally of the cover member.

<13>

In the non-contact rotation sensor according to item 12, a controlcircuit including a circuit device for processing an output signal fromthe magnetic sensor element is connected to the outer surface of thecover member made of resin directly or through the board.

<14>

In the non-contact rotation sensor according to item 12, a controlcircuit including a circuit device for processing an output signal fromthe magnetic sensor element is connected to the outer surface of thecover member made of resin through the board, and the magnetic sensorelement is mounted on the board.

<15>

In the non-contact rotation sensor according to item 12, a controlcircuit including a circuit device for processing an output signal fromthe magnetic sensor element is connected to the outer surface of thecover member made of resin through the board, the magnetic sensorelement is mounted on the board, and a radiating member is put betweenthe board and the cover member.

<16>

In the non-contact rotation sensor according to item 12, the radiatingmember is made of nonmagnetic steel.

<17>

In the non-contact rotation sensor according to any one of items 12 to16, the magnetometric sensor element is an MR element.

<18>

In the non-contact rotation sensor according to any one of items 12 to16, the magnetometric sensor element is a GMR element.

<19>

In a module to change a driving condition of a vehicle comprises areceiving casing for receiving a motor for rotating and driving a shiftrail of a transfer case and a gear mechanism for transmitting rotationof the motor to the shift rail, a control circuit of the motor ismounted on the outer circumference of the receiving casing, and having acover member for forming a closed space for receiving the controlcircuit, and the closed space is communicated with open air through adrain hole or a ventilation hole.

<20>

In the module to change a driving condition of a vehicle according toitem 19, the drain hole or the ventilation hole is bored on the side tobe the ground side with the receiving casing mounted on the motorvehicle.

<21>

In a control device for switching the drive state of a motor vehiclecomprising a receiving casing for receiving a motor for rotating anddriving a shift rail of a transfer case and a gear mechanism fortransmitting rotation of the motor to the shift rail, a control circuitof the motor is mounted on the outer circumference of the receivingcasing, and providing a cover member for forming a closed space forreceiving the control circuit.

<22>

In a module to change a driving condition of a vehicle comprising acasing having a receiving recess for receiving a motor for rotating anddriving a shift rail of a transfer case and a gear mechanism fortransmitting rotation of the motor to the shift rail, an opening of thereceiving recess of the casing is blocked by a cover member having aspace in which the control circuit of the motor is closed and received.

<23>

In a module to change a driving condition of a vehicle comprising areceiving casing for receiving a motor for drivingly rotating a shiftrail of a transfer case and a gear mechanism for transmitting rotationof the motor to the shift rail, a control circuit of the motor beingmounted integral with the receiving casing, on the control circuit ofthe motor are arranged a sensor for detecting a rotating position of theshift rail; an amplifier for amplifying a signal of the sensor; a signalterminal for receiving a desired position signal of the shift rail; anoutput terminal for supplying power to the motor; a motor drive circuitconnected to the output terminal to control a power supply to the motor;and a microcomputer for outputting a control signal to the motor drivecircuit on the basis of a signal received by the signal terminal and asignal from the sensor.

<24>

In the module to change a driving condition of a vehicle according toitem 23, the control circuit of the motor further comprises a lamp drivecircuit for receiving a command signal from the microcomputer to controlof feed to a lamp indicative of a control position of the shift rail,and a lamp signal output terminal for outputting an output signal fromthe lamp drive circuit to outside.

<25>

In the module to change a driving condition of a vehicle according toitem 23, the control circuit of the motor further comprises a lamp drivecircuit for receiving a command signal from the microcomputer to controlpower supply to a lamp indicative of a control position of the shiftrail, and a lamp signal output terminal for outputting an output signalfrom the lamp drive circuit to outside.

<26>

In a module to change a driving condition of a vehicle comprising areceiving casing for receiving a motor for rotating and driving a shiftrail of a transfer case and a gear mechanism for transmitting rotationof the motor to the shift rail, a control circuit of the motor beingmounted integral with the receiving casing, on the control circuit ofthe motor are arranged a sensor for detecting a rotating position of theshift rail, an amplifier for amplifying a signal of the sensor, a signalterminal for receiving a desired position signal of the shift rail, anoutput terminal for supplying power to the motor, a motor drive circuitconnected to the output terminal to control a power supply to the motor,and a microcomputer for outputting a control signal to the motor drivecircuit on the basis of a signal received by the signal terminal and asignal from the sensor. The case is integrally formed with twoconnectors; one of the two connectors is provided with a command inputterminal to which the signal terminal is connected, a power terminal andan earth terminal; the other is provided with a motor power supplyterminal to which the output terminal is connected.

<27>

In the module to change a driving condition of a vehicle according toitem 26, the control circuit of the motor further comprises a lamp drivecircuit for receiving a command signal from the microcomputer to controlpower supply to a lamp indicative of a control position of the shiftrail, a lamp signal output terminal for outputting an output signal fromthe lamp drive circuit to outside, and the one of the two connectors isfurther provided with a lamp signal terminal to which the lamp signaloutput terminal is connected.

<28>

In the module to change a driving condition of a vehicle according toitem 23 or 26, the drive circuit is installed between the microcomputerand the terminal, and the sensor is installed close to the microcomputeraway from the drive circuit.

<29>

A rotation detector comprises a magnet mounted on a rotational body, anda detection element for detecting a change in magnetic field of themagnet which changes according to a rotating position of the rotationalbody, wherein a magnetic material is provided between the rotationalbody and the magnet.

<30>

A rotation detector comprises a magnet mounted on a rotational body, adetection element for detecting a change in magnetic field of the magnetwhich changes according to a rotating position of the rotational body,and a processing circuit for signal processing an output of thedetection element to detect a rotating position of 360 degrees of therotational body, wherein the detection element outputs two sinusoidalwave signals which are different in phase, and the processing circuitsynthesizes signal changes of four 90-degrees sections which are uniformin signal change with respect to rotation of the two sinusoidal wavesignals to detect a rotating position of 360 degrees.

<31>

A shift controller to change a driving condition of a vehicle comprisesan output member for applying an operating force to a device forswitching a drive force transmission channel to wheels of a motorvehicle, a motor for generating the drive force for rotating the outputmember, a gear for transmitting the drive force of the motor to theoutput member, a gear case in which the motor, the gear and the outputmember are received, a sensor for detecting a rotation angle of theoutput member, and a control circuit board including a control circuitof the motor, wherein the control circuit board and a gear receivingportion are isolated by a partitioning wall mounted on the controlcircuit board.

<32>

In the shift controller to change a driving condition of a vehicleaccording to item 31, a magnet is arranged so as to rotate insynchronism with the output member, an MR element which is a sensorelement which reacts in the direction of magnetic field is arranged onthe control circuit board, and a processing circuit for signalprocessing an output signal of the MR element is provided on the controlcircuit board.

<33>

In the shift controller to change a driving condition of a vehicleaccording to item 32, the MR element is a GMR element.

<34>

In the shift controller to change a driving condition of a vehicleaccording to item 32 or 33, there is provided a processing function(arithmetic algorithm) for linearizing the output of the sensor elementfor each specific region, connecting the respective regions, andcontinuously detecting the rotation angle of the rotational body over360 degrees

<35>

In the shift controller to change a driving condition of a vehicleaccording to item 32 or 33, a radiating plate which is a non-magneticbody is provided for radiation of the control circuit board.

<36>

In the shift controller to change a driving condition of a vehicleaccording to item 32 or 33, a yoke member made of magnetic material isarranged at a position in contact with the magnet and at a positionopposite the sensor element.

<37>

In the shift controller to change a driving condition of a vehicleaccording to item 32 or 33, there is provided a sensor mechanism forcanceling by calibration a difference between parts of the sensorelement output for each product.

<38>

In the shift controller to change a driving condition of a vehicleaccording to item 32 or 33, there is provided a function of processingthe sensor element output and a temperature sensor output arranged onthe control circuit board by the control circuit, and compensating thesensor element output for the temperature characteristic thereof.

<39>

In a shift controller to change a driving condition of a vehicle, havingan output member for applying an operating force to a device forswitching a drive force transmission channel to wheels of a motorvehicle, a motor for generating the drive force for rotating the outputmember, a gear for transmitting the drive force of the motor to theoutput member, a gear case in which the motor, the gear and the outputmember are received, and a control circuit board including a controlcircuit of the motor, a magnet rotated in synchronism with the outputmember is provided, and a MR element which is a sensor element whichreacts in the direction of magnetic field is arranged on the controlcircuit board and within the magnetism distribution of the magnet.

<40>

In the shift controller to change a driving condition of a vehicleaccording to item 39, the MR element is a GMR reactive in the directionof magnetic field.

<41>

In the shift controller to change a driving condition of a vehicleaccording to item 39 or 40, there is provided a processing function(arithmetic algorithm) of linearizing the output of the sensor elementfor each specific region, connecting the respective regions, andcontinuously detecting the rotation angle of the rotational body over360 degrees.

<42>

In the shift controller to change a driving condition of a vehicleaccording to item 39 or 40, a radiating plate which is a non-magneticbody is provided for radiation of the control circuit board.

<43>

In the shift controller to change a driving condition of a vehicleaccording to 39 or 40, a yoke member made of magnetic material isarranged at a position in contact with the magnet and at a positionopposite to the sensor element.

<44>

In the shift controller to change a driving condition of a vehicleaccording to item 39 or 40, there is provided a function of canceling adifference between parts of the sensor element output for each product.

<45>

In the shift controller to change a driving condition of a vehicleaccording to 39 or 40, there is provided a function of processing thesensor element output and the temperature sensor output arranged on thecontrol circuit board by the control circuit, and compensating thesensor element output for the temperature characteristic thereof.

<46>

In a shift controller to change a driving condition of a vehicle, havingan output member for applying an operating force to a device forswitching a drive force transmission channel to wheels of a motorvehicle, a motor for generating the drive force for rotating the outputmember, a gear for transmitting the drive force of the motor to theoutput member, a gear case in which the motor, the gear and the outputmember are received, a sensor for detecting a rotation angle of theoutput member,

a control circuit board formed with a processing circuit having a signalprocessing function of the sensor, a board case on which the circuitboard is mounted, and a construction for covering the gear by the gearcase and the board case, a worm gear is included in the constitutionalelements of the gear, and the rotating shaft of the output member andthe rotating shaft of the motor are positioned vertically each other.

<47>

In a shift controller to change a driving condition of a vehicle, havingan output member for applying an operating force to a device forswitching a drive force transmission channel to wheels of a motorvehicle, a motor for generating the drive force for rotating the outputmember, a gear for transmitting the drive force of the motor to theoutput member, a gear case in which the motor, the gear and the outputmember are received, a sensor for detecting a rotation angle of theoutput member,

and a control circuit board including the control circuit of the motor,there is provided a construction in which a plurality of gears aremeshed and connected through a gear holder.

<48>

In a shift controller to change a driving condition of a vehicle, havingan output member for applying an operating force to a device forswitching a drive force transmission channel to wheels of a motorvehicle, a motor for generating the drive force for rotating the outputmember, a gear for transmitting the drive force of the motor to theoutput member, a gear case in which the motor, the gear and the outputmember are received, a sensor for detecting a rotation angle of theoutput member,

and a control circuit board including the control circuit of the motor,a terminal of the motor is connected to a terminal of the controlcircuit board by fitting connection.

<49>

In a shift controller to change a driving condition of a vehicle, havingan output member for applying an operating force to a device forswitching a drive force transmission channel to wheels of a motorvehicle, a motor for generating the drive force for rotating the outputmember, a gear for transmitting the drive force of the motor to theoutput member, a gear case in which the motor, the gear and the outputmember are received, a sensor for detecting a rotation angle of theoutput member,

and a control circuit board including the control circuit of the motor,a board case for receiving the control circuit board or a cover joinedto the board case is provided with a ventilation hole.

<50>

A non-contact magnetometric rotation angle sensor is constituted by amagnet mounted on a rotational body, an MR element positioned within amagnetism distribution space of the magnet and reactive in the directionof magnetic field, and a signal processing circuit board having aprocessing circuit for approximating an output signal of the MR elementevery specific region with respect to a rotation angle of the rotationalbody with a multi function, uniting divided regions and outputting asignal linearized over 360 degrees.

<51>

In the non-contact magnetometric rotation angle sensor according to item49, the MR element is a GMR element which is reactive in the directionof magnetic field.

<52>

In the non-contact magnetometric rotation angle sensor according to item49 or 50, the multi function is calculated by calibration.

<53>

In the non-contact magnetometric rotation angle sensor according to item49 or 50, there is provided a holding plate which is non-magnetic bodyfor holding the signal processing circuit board.

<54>

In the non-contact magnetometric rotation angle sensor according to item49 or 50, a yoke member made of magnetic material is arranged at aposition in contact with the magnet and at a position opposite thesensor element.

<55>

In the non-contact magnetometric rotation angle sensor according to item49 or 50, there is provided a function in which the sensor elementoutput and an output of a temperature sensor arranged on the signalprocessing circuit board are processed by the signal processing circuit,and the sensor element output is compensated for the temperaturecharacteristic thereof.

<56>

In the non-contact magnetometric rotation angle sensor according to item49 or 50, wherein the rotational body and the sensor element areisolated by a non-magnetic body.

BRIEF DESCRIPTION OF THE DRAWINGS

Other objects and advantages of the invention will become apparent fromthe following description of embodiments with reference to theaccompanying drawings in which:

FIG. 1 is an entire constitutional view of a motor vehicle for which ashift controller is used according to one embodiment of the presentinvention;

FIG. 2 is an exploded perspective view on the cover side of the shiftcontroller according to one embodiment of the present invention;

FIG. 3 is an exploded perspective view of a gear mechanism used for theshift controller according to one embodiment of the present invention;

FIG. 4A is an exploded perspective view on the housing side of the shiftcontroller according to one embodiment of the present invention;

FIG. 4B is a top view on the housing side of the shift controlleraccording to one embodiment of the present invention;

FIG. 5 is a longitudinal sectional view of a rotation detection deviceaccording to one embodiment of the present invention;

FIG. 6 is an explanatory view of the principle of the rotation detectiondevice according to one embodiment of the present invention;

FIG. 7 is an explanatory view of the effect of the rotation detectiondevice according to one embodiment of the present invention;

FIG. 8 is an explanatory view showing examples (a)-(d) of magnets usedfor the rotation detection device according to one embodiment of thepresent invention;

FIG. 9 is a longitudinal sectional view of the shift controlleraccording to one embodiment of the present invention;

FIG. 10 is an explanatory view of operation of the shift controlleraccording to one embodiment of the present invention;

FIG. 11 is an explanatory view showing a concrete example of a circuitboard of the shift controller according to one embodiment of the presentinvention;

FIG. 12 is a function block diagram of the shift controller according toone embodiment of the present invention;

FIG. 13 is a exploded perspective view for explaining an assembly of theshift controller according to one embodiment of the present invention;

FIG. 14 is a perspective view for explaining an action of a gearmechanism of the shift controller according to one embodiment of thepresent invention.

FIG. 15 is a function block diagram of the rotation angle detectiontechnique according to one embodiment of the present invention;

FIG. 16 is a waveform diagram for explaining the rotation angledetection technique according to one embodiment of the presentinvention;

FIG. 17 is a circuit diagram for explaining part of a circuit of theshift controller according to one embodiment of the present invention;

FIG. 18 is a characteristic diagram for explaining temperaturecompensation technique of a sensor according to one embodiment of thepresent invention; and

FIG. 19 is a function block diagram for explaining the temperaturecompensation technique of the sensor according to one embodiment of thepresent invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

One embodiment will be described hereinafter on the basis of an exampleapplied to a two-wheel drive/four-wheel drive switching shiftcontroller.

<Four-Wheel Drive>

First, referring to FIG. 1, a four-wheel vehicle drive train isschematically shown by reference numeral 27. The four-wheel vehicledrive train 27 includes an electric motor or prime mover 35 which iscoupled to and directly drives a transmission 31. The transmission 31may be either automatic or manual type. The output of the transmission31 directly drives a transfer case assembly 33 which provides motivepower to a primary or rear drive line 40 comprising a primary or rearprop shaft 37, a primary or rear differential 38, a pair of live primaryor rear axles 39, and a respective pair of primary or rear tire andwheel assemblies. The transfer case assembly 33 selectively providesmotive power to a secondary or front drive line 30 comprising asecondary or front prop shaft 32, a secondary or front differentialassembly 34, a pair of live secondary or front axles, and a respectivepair of secondary or front tire and wheel assemblies 28. The front tireand wheel assemblies 28 may be directly coupled to a respective one ofthe pair of secondary or front tire and wheel assemblies 28.Alternatively, a pair of manually or remotely activable locking hubs 42may be operably disposed between the pair of front axles 36 and arespective one of the tire and wheel assemblies 28 to selectivelyconnect same. Both the primary drive line 40 and the secondary driveline 30 may include suitable and appropriately universal joints 44 whichfunction to allow static and dynamic offsets and misalignments betweenvarious shafts and components.

<Mode Switching Switch>

A control console or assembly 46 which is preferably disposed withinconvenient reach of the vehicle operator includes a switch 48 whichfacilitate selection of the operating mode of the transfer case assembly33.

<Control Module for a Shift Controller>

A mechanical-electrical integrated type shift controller bearing controlof a shift rail 54 of the transfer case assembly 33 is called a shiftcontroller 41. The shift controller 41 is mounted on the transfer caseassembly 33. The shift controller 41 has an output shaft bored with acounterbore, and is connected to the shift rail 54 of the transfer caseassembly 33 through the output shaft. The shift controller 41 receivesan output signal of the mode switching switch 44, vehicle speedinformation from the engine control unit, engine rotation frequencyinformation, throttle position information, and has a function ofcausing the output shaft to follow the target rotation angle.

FIG. 2 is an exploded perspective view of the mechanical-electricalintegrated type shift controller 41 which best represents thecharacteristics of the present invention. In FIG. 2, a motor 16 forgenerating the drive force has a first gear 21 as an output stage gearmounted on a motor output shaft of the motor 16, is received into amotor receiving portion of a gear case 17, and is secured to the gearcase 17 by means of a metal band 16 a. An intermediate rotating shaft23, a second gear 19 and a third gear 13 are molded integrally, and asmaterials for the intermediate rotating shaft 23, the second gear 19 andthe third gear 13, iron, aluminum, resins or the like may be employed,but in the present invention, iron material which is highest in strengthis employed. The second gear 19 is arranged so as to mesh with the firstgear 21, and the third gear 13 is arranged through a gear holder 12 soas to mesh with a fourth gear 20 molded integral with an output rotatingshaft 11. As a result, the rotating shaft of the motor 1 and the outputrotating shaft 11 are arranged at right angles. The gear mechanism isconstituted as described above to thereby provide an advantage that aclearance between the gears can be made smaller than the case where thegear mechanism is constituted merely by a plane gear. The outputrotating shaft 11 is formed at its extreme end with a counterbore, andengaged so as to transmit torque by fitting with a shift rail 54 (seeFIG. 9) of the transfer case assembly 33. A magnet holder 10 is fittedin the upper surface of the fourth gear 20 or connected by bonding. Ayoke 9 made of a magnetic material is connected to the magnetic holder10 by fitting or bonding, and a magnet 8 is connected to the magneticyoke 9 by fitting or bonding. The magnet 8, the magnetic yoke 9, themagnet holder 10 and the output rotating shaft 11 are all connected soas to be rotated synchronously. In FIG. 2, a connector 18 is moldedintegrally with a board case 6 also serving as a gear cover, and theconnector 18 is used for communication with the shift controlleroutside, supply of power supply, and input of an ignition signal. Aheatsink or radiating plate 5 is bonded to the board case 6 with anepoxy or silicone adhesive bond, and a circuit board 2 is bonded to theheatsink 5 with the epoxy or silicone adhesive bond. A sensor 3, amicrocomputer 4, and EEPROM 24 are mounted on the circuit board 2, and aboard cover 1 is bonded to the board case 6 with the epoxy or siliconeadhesive bond so as to cover the circuit board 2. As shown in FIGS. 4Aand 4B, the board case 6 is connected to a gear case 17 by screwing orthe like through a seal material 7. At that time, the circuit board 2and the terminal of the motor 16 are electrically connected through amotor connection terminal A14 and a motor connection terminal B15. Thegear case 17 has a motor housing portion and a gear mechanism housingportion which are a metal housing. The board case 6 is secured to ahousing (gear case 17) which is a resin cover with the seal 7 puttherebetween, both of which define a space for receiving the motor andthe gear mechanism. As described, the board case 6 is also provided witha function of covering the motor and the gear mechanism in which senseit can be called a motor cover or a gear cover.

As for the mounting position of the motor, the motor and theintermediate rotating shaft may be arranged in parallel with each other,in addition to that shown in FIG. 9.

<Constitution of an Angle Detection Portion>

FIG. 3 is a sectional view of a portion for detecting a rotation angleof an output rotating shaft 11. In FIG. 1 or FIG. 3, a magnet holder 10is connected in contact with the output rotating shaft 11 so as torotate synchronously with the output rotating shaft 11. The magnetholder 10 is provided with a groove for fixing a magnet 8 and a magneticyoke 9 in a stabilized condition. It is desired that the magnet 8 andthe magnetic yoke 9 are in contact, and in the present invention, theyare bonded to each other using an epoxy adhesive bond, but the magnet 8and the magnetic yoke 9 may be molded integrally. The magnet 8 and themagnetic yoke 9 are adhered to the magnet holder 10 with an epoxyadhesive bond. However, fitting-in or insert molding of the magnet 8 andthe magnetic yoke 9 at the time of molding the magnet holder 10 is alsoenabled. The lower surface of the board case 6 is positioned away fromthe upper surface of the magnet 8, as shown in FIG. 2. The heatsink 5 isconnected to the board case 6 with an epoxy or silicone adhesive bond,and the circuit board 2 is connected to the heatsink 5 by the epoxy orsilicone adhesive bond. The sensor element 3 is arranged within amagnetism distribution space of the magnet 8 and on the circuit board 2.In this case, it is desired that the sensor element 2 is disposed on therotating shaft of the magnet 8, but generally, a deviation occurs due tothe assembling tolerance or the like. However, if the center of thesensor element 3 is disposed within a circle of about 5 mm in diameter,it can be corrected by a calibration described later.

A main function of the shift controller 41 is to cause the rotationangle of the output rotating shaft 11 to follow the target rotationangle. To this end, it is necessary to detect the rotation angle of theoutput rotating shaft 11 with high accuracy. Further, the rotationoperating range of the output rotating shaft 11 is from 0 to 280degrees, and a mechanism capable of detecting an angle oversubstantially whole region (360 degrees) is necessary. Various systemsfor detecting a rotation angle such as a non-contact type using a Holeelement have been heretofore devised. In the present invention, themagnet 8 is secured to the output rotating shaft 11, and a change ofdirection of the magnetic field is detected using the sensor element 3on the circuit board 2 to thereby realize the detection of the rotationangle over the whole region (360 degrees)

Attention should be paid generally in using the magnet to the unexpecteddisturbance of a magnetic circuit. In the present invention, it isfeared that a first gear 21, a second gear 19, a third gear 13, a fourthgear 20 and the output rotating shaft 11 are possibly formed of magneticbodies such as iron to give unexpected influence to the magnetic circuitaround the magnet 8. Accordingly, it is necessary that the magnet 8 isdistanced to some extent from the magnetic bodies such as the first gear21, the second gear 19, the third gear 13, the fourth gear 20 and theoutput rotating shaft 11. In the present invention, the magnetic bodyclosest to the magnet 8 is the output rotating shaft 11, and withrespect to coercive force 304 (KA/m) and the remanent flux density 470(mT), the distance between the magnet 8 and the output rotating shaft 11is 20 mm. In order not to affect on the magnetic circuit around themagnet, the magnetic holder 10 will suffice to be a non-magnetic body,and in consideration of the processing property or the rigidity, resinor aluminum may be employed. In the present invention, the resin isemployed.

The magnetic holder 10 keeps the distance between the magnet 8 and theoutput rotating shaft 11 constant and further has a function of securingthe magnet 8 to the shaft B11 so that the magnet 8 may be rotated insynchronism with the output rotating shaft 11. Further, the magnetholder 10 also bears a function of adjusting the distance (hereinafterreferred to as the air gap) between the magnet 8 and the sensor element3. This air gap is very important, and where the air gap is too longerthan the set value, the magnetic force of the magnet 8 reaching thesensor element 3 is so small that the sensor element 3 cannot beactivated. Contrary to this, where the air gap is shorter than the setvalue, the magnet 8 comes in contact with the board case 6 to impair therotational motion of the output rotating shaft 11, or the magnetic forceapplied to the sensor element 3 is too large that unexpected damage ispossibly given to the sensor element 3.

Next, designing of the magnetic circuit using the magnetic yoke 9 willbe mentioned. Where the magnetic body is not present around the magnet8, magnetism radiated from the magnet 8 flows from N pole to S polesubstantially symmetrically with respect to a plane around the magnet(see FIG. 6A). Accordingly, magnetism is generated also in a spaceopposite a space where the sensor element 3 is positioned, failing torealize an effective magnetic circuit. Therefore, the magnetic yoke 9 isarranged so as to come in contact with a lower part of the magnet 8(opposite the sensor element 3) in order to realize the effectivemagnetic circuit (see FIG. 6B). However, the magnetic yoke 9 should be amagnetic body. Further, attention should be paid to the shape of themagnetic yoke. If the magnetic yoke 9 is thin, the magneticcharacteristic of the magnetic yoke becomes saturated, and magnetismleaking into the external space of the magnetic yoke 9 increases,failing to constitute an effective magnetic circuit. Accordingly, thethickness of the magnetic yoke 9 will suffice to be a thickness to adegree that the magnetic characteristic of the magnetic yoke is notsaturated, and relies upon the magnetic characteristic of the magnet 8.In the case of the present invention, the thickness of the magnetic yoke9 with respect to the magnet 8 is desirably not less than 2 mm, andactually 3 mm is employed. It is desired that a sectional area of themagnetic yoke 9 in a direction vertical to the rotating shaft is equalto that of the magnet 8. The reason is that if the sectional area is toowide, the magnetic circuit at the lower part of the magnet becomeswidened, whereas it is too narrow, the component which does not passthrough the magnetic yoke 9 among the magnetism radiated form the lowerpart of the magnet increases. The influence of the presence and absenceof the magnetic yoke 9 was obtained by analysis. The results are shownin FIG. 7.

In FIG. 5, the solid line represents the case where the magnetic yoke ispresent, and the broken line represents where the magnetic yoke isabsent. The magnetic yoke 9 having the shape as described is employedwhereby the magnetic circuit at the lower part of the magnet 8 islimited to a determined space (see FIG. 4(b)), and the magnetic forceapplied to the sensor element 3 can be strengthened about 40 percent ascompared with the case where the magnetic yoke 9 is absent. Accordingly,by using the magnetic yoke 9, the effective magnetic circuit can berealized. In the present invention, SUS430 is used for the magnetic yoke9, but even the magnetic body having the magnetic characteristic equalthereto, for example, such as S45C or S15C can be applied to the presentinvention.

Further, in the present invention, when the magnetic force which passesthrough the sensor element 3 is within the range of from 10 kA/m to 15kA/m, the output of the sensor element 3 reacts in the direction of amagnetic field which passes through the sensor element 3 is not affectedby the magnitude of magnetic field. Further, the circuit board 2, theheatsink 5, and the board case 6 are positioned between the magnet 8 andthe sensor element 3, of which thicknesses are about 1 mm, about 2 mmand about 2 mm, respectively. When the distance from the board case 6 tothe surface of the magnet 8 is set to about 1 mm, the distance betweenthe magnet 8 and the sensor element 3 is 6 mm in total. In considerationof the election tolerance or the process tolerance, that distance isabout 6 mm±1 mm. Therefore, material and shape of the magnet 6 aredetermined from the condition of distance (about 6 mm±1 mm) and thecondition of the magnetic force which passes through the sensor element3 (10 kA/m to 15 kA/m). Table 1 shows the magnetic material and itscharacteristics being used at present. In the present invention, a SmFeNmagnet which is in better conditions is employed. It is desired that thedirectivity of magnetic field passing through the sensor element 3 is insynchronism with the rotation of the magnet 8. Because of this, it isdesired that the shape of the magnet is symmetrical about the centershaft, and as shown in FIG. 8, a disk shape, a donut shape, atrapezoidal shape, a bar-like shape or the like may be employed. In thepresent invention, a bar-like magnet (20 mm×4 mm×3 mm) is used inconsideration of easiness of processing. TABLE 1 TEMPER- ATURE COEF-PRICE Hc FICIET (FER- PRODUC- JUDGE- KIND Br(T) (kA/m) OF Br RITE)TIVITY MENT Ferrite X 0.2 X 150 X −0.18 ⊚ 1 X DIF- X FICULT Alnico ◯ 0.6X 45 ⊚ −0.02 ◯  5-10 X DIF X FICULT SmFeN ◯ 0.47 ◯ 304 ◯ −0.06 ◯ 10-15 ◯EASY ⊚ Nd-Fe-B ⊚ 1.2 ◯ 880 X −0.13 ◯ 15-20 ◯ EASY X Sm-Co ◯ 0.9 ◯ 690 ◯−0.04 X 20-25 ◯ EASY X

<Isolation Constitution of a Circuit Portion>

FIG. 9 shows the internal constitution of the shift controller 41. In agear chamber 40 formed by the gear case 17 and the board case 6 arearranged mechanical portions including the rotational bodies such as thefirst gear 21, the second gear 19, the third gear 13, the gear holder12, the magnet 8, the magnetic yoke 9 and the like. In the board case 6is arranged a board chamber 66 including the circuit board 2, theheatsink 5, the sensor element 3, the microcomputer 4 and the like so asto be isolated from the gear chamber 40 through the gear chamber 40 andthe board case 6. With this configuration, it is possible to protect thecircuit board 2 from the substances such as dust, oil or the likecontemplated to be generated in the mechanical portions, whichsubstances adversely affects on an electronic circuit. Further, itbecomes possible to realize the choice of a variety of assembling stepssuch that the mechanical portions and the electronic circuit portion arefabricated in a remote place, they are transported to a place where theycan be assembled, and they are assembled later. Further, as shown inFIG. 10, there is contemplated as a partitioning wall for isolating aboard chamber 66 from the gear chamber 40, a combination of the board orthe board case or a heatsink 56 or a gear case 55 and the board or theboard case or a heatsink 56. Further, as a mounting position of a boardchamber 66, there is contemplated on the rotating shaft of the finaloutput shaft or on the rotating shaft of the intermediate gear.

<Radiation of the Board>

It is determined that the range of operating ambient temperature of theshift controller 41 is from −40 degrees to 125 degrees. In particular,the operation at high temperature poses a problem, and at the time ofdriving the motor 16, the rise of temperature of the circuit board 2 isexpected. Under the temperature conditions exceeding 150 degrees, theoperating compensation of the microcomputer cannot be done, and measuresfor radiation at the time of high temperature need be made without fail.Therefore, the heatsink 5 is disposed between the board case 6 and thecircuit board 2. The purpose of arranging the heatsink 5 is for themeasure for radiation, but simultaneously bears a function of areinforcing material for the circuit board 2. Accordingly, as thematerial for the heatsink 5, those having high heat conductivity andhigh strength are desirable. Further, the heatsink 5 is disposed betweenthe magnet 8 and the sensor element 3, and should not impair themagnetic circuit. Therefore, the heatsink 5 need be a non-magnetic bodywhich does not affect on the magnetic circuit. In the present invention,aluminum (Al) is employed as material for the heatsink 5 inconsideration of the foregoing conditions.

<Circuit Board>

The circuit board 2 is arranged between the magnet 8 and the sensorelement 3 not to impair the magnetic circuit. Therefore, a material forthe circuit board 2 is a non-magnetic body similar to the heatsink 5.Furthermore, in order to effectively radiate heat generated on thecircuit board 2, the material is necessary to be high in heatconductivity. In the present invention, aluminum (Al₂O₃) is employed.FIG. 11 shows an arrangement of circuit parts on a circuit board 2. Onthe circuit board 2 are arranged a microcomputer 4, a sensor element 3,an amplifier 45, a motor drive circuit element 47, EEORIN 24, aregulator 49 and the like. These are connected to electrically oneanother and bear the control of the shift controller.

The position of the microcomputer 4 is not particularly regulated butany position will suffice as long as it is on the circuit board 2. Themicrocomputer 4 is operated in accordance with a predetermined program,and bears a function of deciding and controlling the operation of theshift controller. The concrete functions of the shift controller involvecommunication with the engine controller, output signal processing ofthe sensor element 3 described later, control of the motor 16 and thelike. To this end, the microcomputer 4 or the circuit board 2 on whichthe microcomputer 4 is arranged need to provide a PWM output/sensorelement signal for the motor control, and an A/D input for input of atarget angle signal. In the present invention, H85/261 made by HitachiSeisakusho is used as the microcomputer 4. The microcomputer 4 isprovided with functions of an electrically re-writable flush memory, anA/D conversion input, a timer and the like.

The position of the sensor element 3 is within the magnetic distributionspace of the magnet 8 and on the rotating shaft of the output rotatingshaft 11, and it is desired that the arrangement surface of the sensorelement 3 is parallel with the rotational surface of the magnet 8.However, actually, there are an error in the assembling step and anerror in part processing, and a deviation is present in both coaxialityand parallelism. The deviation of both coaxiality and parallelism is oneof causes that cannot be ignored of affecting on the output of thesensor element 3. In the present invention, the sensor elementcalibration described later is carried out in all the shift controllerin order to remove the aforementioned influence.

FIG. 12 shows a circuit function block on the circuit board. Since theamplitude of an output signal of a sensor element 3 is approximately 100mV (at the time of 5 V supply), it is necessary for detecting an anglewith higher accuracy to amplify the output signal of the sensor element3 to input it into the microcomputer 4. To this end, the amplifier 45bears a function of amplifying the output of the sensor element 3 tooutput it to the microcomputer 4.

The EEPROM 24 is used to store constant calculated in the sensor elementcalibration or to record the conditions of the shift controller 41.

The motor drive circuit element 47 comprises a H bridge circuit, andcauses drive current to flow to the motor 16 in response to a motordrive command signal such as PWM output by the microcomputer 4.

One of the characteristics of the present invention lies in that on thecircuit board 2 are arranged all circuit parts such as the microcomputer4, the sensor element 3, the amplifier 45, the motor drive circuitelement 47, the EEPROM 24, the regulator 49 and the like. This enablesplanning not only reduction of the number of parts such that a wiringbetween the sensor element 3 and the microcomputer 4, but alsoenhancement of reliability. Furthermore, exclusive mounting members forthe sensor element need not be provided, and simplification of thesensing portion, reduction in the board size, and reduction in the shiftcontroller size can be planned. Further, since a material for the boardis aluminum, all or some of ICs can be mounted in the state of thepaired chips. In the present invention, the regulator 49, the amplifier45, the motor drive circuit element 47, and the lamp drive IC 50 aremounted in a bear-chip manner.

<Board Cover>

A board cover 1 is provided over the circuit board 2. The circuit board2 is protected from the external causes such as water, dust or oil bythe board case 6 and the board cover 1.

<Ventilation Hole>

However, in consideration of the using environmental conditions and themanufacturing process of the shift controller, there is feared of thechange in temperature of a space in which the circuit board 2 is storedand arranged (hereinafter referred to as a board chamber 66). Forexample, at high temperature, internal air of the base late chamber 66is inflated, but at low temperature, it is contracted. When the boardchamber 66 is completely sealed from the external space, ventilationbecomes disabled, and stress caused by inflation and contraction of airis applied to the board cover 1 and the board case 6. The board cover 1or the board case 6 is probably broken due to the stress. Only the meansfor solving this problem is to provide a ventilation portion in theboard case 6 or the board cover 1. The desirable conditions of theventilation portion is excellent in water resistance, repellingproperties, oil resistance, and heat resistance, and are able to realizestabilized and continuous ventilation. In the present invention, aventilation portion 43 having a diameter of 1 mm is provided on theboard cover 1, and a seal material having a porous construction isattached so as to cover the ventilation portion 43.

<Motor Connection Terminal>

The motor drive current and the motor 16 on the circuit board 2 have tobe connected electrically. As the concrete means, a conductor is used.In this method, however, after the circuit board 2, the motor 16 and thelike have been assembled, the circuit board 2 and the motor 16 have tobe joined newly by soldering or the like, which is not desirable interms of work efficiency. Therefore, for connection of the circuit board2 and the motor 16, fitting joining using an exclusive-use terminal orthe like is desired. In the present invention, there is employed, forsimplifying the assembling process, the construction in which the motorconnection terminal A14 and the motor connection terminal B15 are moldedintegrally with the board case 6, which is fitted and joined to themotor terminal. This is a devise that after the circuit portion 25 andthe mechanical portion 26 have been combined, both the portions aremerely combined together whereby the circuit board 2 and the motor 16are connected to each other (see FIGS. 4A, 4B and 13).

<Gear Constitution>

In the present embodiment, one characteristic is the arrangementconstitution of the motor and the gear. In the assembling process of themechanical portions, portions which require extreme time and techniqueare assembling and mounting steps of the motor and the gear. Forsimplifying the steps, there is employed the construction that the motor16, the gear holder 12 and the output rotating shaft 11 can be assembledand mounted in the same direction with respect to the gear case 17 (seeFIG. 3), and further, as will be understood from FIG. 13, there isconstructed that the height of the motor 16 and the gear holder 12 ishigher than that of the gear case 17.

<Gear Set>

FIG. 14 shows the constitution of a gear set. The gear holder 12 has twothrough-holes for bearings. The intermediate rotating shaft 23 integralwith the second gear 19 and the third gear 13is fitted and connected inone through-hole, and fixed axially by means of the clip 22. The outputrotating shaft 11 integral with the fourth gear 20 is fitted andconnected in the other through-hole.

It is necessary, for downsizing of the shift controller, to make thesize of the motor small. However, generally, the motor size is in aproportional relation with the motor output torque, and torque enough todrive the transfer case 33 by the output rotating shaft 11 cannot beobtained merely by making the motor size small. Therefore, one or aplurality of gear stages, and torque generated in the motor 16 isamplified and transmitted to the output rotating shaft 11 through thegear stages. In a case of only one gear stage, the gear size of the rearstage becomes large, which is not desirable in terms of miniaturizationof the shift controller 41. Accordingly, there is desired a method inwhich a plurality of gear stages are provided to dispose the gearsefficiently whereby target torque in the output rotating shaft 11 isobtained. However, it is contemplated that by the provision of aplurality of gear stages, energy loss occurs in the respective gearstages. Therefore, a mechanism for raising the energy transmissionefficiency of the gears is necessary. There is contemplated a method forraising the energy efficiency of the gears in which the frictional forcebetween the shaft and the bearing is reduced, and meshing of gears ismaintained in the ideal condition. The present embodiment employs adevise that the distance between the axial centers of the third gear 13and the fourth gear 20 can be maintained constant by using the gearholder 12. Furthermore, the third gear 13 and the fourth gear 20 areincorporated into the gear holder 12 in advance, and the gear set isformed into module whereby the step when the gears are incorporated intothe gear case 17 becomes easy.

<Sensor Calibration>

Next, the sensor element 3 will be mentioned. Generally, in the sensorof which purpose is to detect a position and detect a rotation angle,where output of the sensor element is of an analogue type, a differencebetween parts occurs in output with respect to an object every sensorelement or every product. The causes of the difference between partsreside in a deviation in position when the sensor element is mounted onthe board, an error at the time of assembly or a difference insensitivity with respect to an object in a single sensor element. Wherethe demand for performance with respect to the sensor element is high,this difference between parts cannot be ignored, and it is necessary toemploy a method for eliminating the difference between parts bycancellation or the like. In the present embodiment, as one method forcanceling the difference between parts, the following calibration isemployed. FIG. 15 shows a block diagram of the sensor elementcalibration.

In the calibration, first, the output rotating shaft 11 of the shiftcontroller 123 and the rotary encoder 116 capable of detecting an angleto be a reference are arranged so that their rotating shafts arecoaxial. Next, the motor 16 within the shift controller 116 is driven torotate the output rotating shaft 11, and simultaneously, a absoluteangle signal from the encoder and an output of the angle sensor element3 are placed in synchronism with each other and read into a computer(117). In the computer, noises of the output signal of the sensorelement 3 are removed (118), and normalization is accomplished so thatthe output of the sensor element 3 is 1 in maximum, and −1 in minimum(109). FIG. 16 shows a relation between the magnet rotation angle andthe normalized signal. The sensor element 3 employed in the presentembodiment has outputs of two systems, and the output signals aresignals which are deviated in phase each other with respect to thedirection of magnetic field passing through the sensor element 3. Next,the output signal of the sensor element 3 with respect to the magnetrotation angle is divided into four regions using normalized two signalsand two thresholds (120). Table 2 shows the respective regions andconditions. TABLE 2 SENSOR OUTPUT USED FOR CALCULATION REGION CONDITIONS(: = v) I OUTPUT 2 ≧ THRESHOLD 1 OUTPUT 1 II OUTPUT 1 ≦ THRESHOLD 2OUTPUT 2 III OUTPUT 2 ≦ THRESHOLD 2 OUTPUT 1 IV OUTPUT 1 ≧ THRESHOLD 1OUTPUT 2

However, it is desired that the threshold level 1 is smaller than thevalue in which the output 1 and the output 2 cross on the positive side,and is desired that the threshold level 2 is larger than the value inwhich the output 1 and the output 2 cross on the negative side. Because,sometimes, where these two conditions are not fulfilled, there ispresent a region which does not belong to any region between theregions, and angles calculated from the sensor element output arediscontinuous. Further, the value in which the output 1 and the output 2cross is different every product due to the influence of the sensorelement or the assembling tolerance. Considering this variation, in thepresent embodiment, the threshold level 1 is set to 0.6, and thethreshold level 2 to −0.6.

Further, due to the approximation in a tertiary expression in therespective regions, the coefficients {a, b, c, d} of a tertiary functionwhich minimizes E in the following Expression are decided.$\begin{matrix}{v_{i\quad n} = {\frac{v_{i} - {\left( {v_{i\_ max} + v_{i\_ min}} \right)/2}}{\left( {v_{i\_ max} - v_{i\_ min}} \right)/2}\left\{ {{i = 1},2} \right\}}} & (1)\end{matrix}$

Wherein θ indicates the absolute angle calculated from the encoderoutput, and v indicates the variable used in the above-describedcalculation in each region, which is displayed by the bold line in FIG.16. n indicates the sampling number in each region, and Xi indicates thei-th value of variable X.

In the present embodiment, since the region is divided into four, thecoefficients to be calculated are 16 in total. Finally, the calculatedcoefficients are written into EEORIN 24 within the shift controller 123and saved (122).

<Sensor Element Temperature Compensation>

Next, the temperature characteristics of the sensor element and thecompensation method thereof will be mentioned. Generally, in thesemiconductor or the sensor element formed of ferromagnetic such asiron, the reactivity with respect to the object or its own resistancevalue changes with temperatures (temperature-dependent). As mentionedhereinbefore, the range of the operating temperature of the shiftcontroller is from −40 degrees to 125 degrees. Further, it is expectedthat the temperature conditions excess the above results momentarily.The influence given to the sensor element by the wide temperature changecannot be ignored, and need be compensated for by any means. In thepresent embodiment, after assembly of products, the sensor elementoutput is subjected to calibration, and the sensor output is calculatedusing the calculated constant. Therefore, temperature compensation iscarried out for the target that even if the temperature is changed, asensor output equal to the sensor element output at the time ofexecution of calibration is obtained in a false manner. It is known thatthe sensor element 3 employed in the present embodiment changes itswhole resistance value by temperatures, and the reactivity with respectto the magnetic field also changes. Further, when the output of thesensor element 3 is input into the microcomputer 4, the signal isamplified by the ope-amp. An offset voltage of the ope-amp is alsotemperature dependent, and in the present embodiment, and it is anobject for compensation similar to the temperature characteristic of thesensor element 3. It is known that in the above-mentioned range ofoperating temperature (−40 degrees to 125 degrees), the change in thetotal resistance of the sensor element 3 changes by about 20%, and thereactivity with respect to the magnetic filed lowers by about 30%. Inthe present embodiment, in connection with the temperaturecharacteristics, correction is carried out by software. By thesetemperature characteristics, there are tendencies that the output signalof the ope-amp lowers in mean value and reduces in amplitude as thetemperature rises. However, since these two tendencies have linearitywith respect to the temperature change, and therefore, correction can bemade by the following Expressions. $\begin{matrix}{E = {\sum\limits_{i = 1}^{n}\left\{ {\theta_{i}^{t} - \left( {{\alpha \cdot v_{1}^{3}} + {b \cdot v_{i}^{2}} + {c \cdot v_{i}} + d} \right)^{2}} \right.}} & (2) \\{v_{i\quad{offsetcomp}}:={v_{i} + {{\alpha_{offset} \cdot \left( {t_{calibration} - t} \right)}\left\{ {{i = 1},2} \right\}}}} & (3) \\{v_{i\quad{ampcomp}}:={\frac{v_{i\quad{offsetcomp}} - v_{i\_ mid}}{{\alpha_{amp} \cdot \left( {t - t_{calibration}} \right)} + 1} + {v_{i\_ mid}\left\{ {{i = 1},2} \right.}}} & (4)\end{matrix}$

Wherein a_(offset)·a_(amp) is constant obtained by experiments or thelike, t_(calibration) is a temperature when calibration is carried out,t is temperature around the sensor element, v_(offsetcomp)·v_(ampcomp)are values for which temperature characteristics of sensor element 3output means value and amplitude are compensated for, andv_(max)·v_(min) are maximum value and minimum value of the sensorelement 3 output when calibration is executed.

<Temperature Calculation>

In the case of the present embodiment, it is necessary to compensate theoutput of the sensor element 3 for the temperature characteristicsthereof, and the temperature over the whole area in the range ofoperating temperature of the shift controller has to be detected. In thepresent embodiment, the circuit of FIG. 17 is used for the temperaturesensor element to obtain an output corresponding to the temperature. Theoutput of the temperature sensor is input into a computer such as amicrocomputer to compute temperatures. If the output of the temperaturesensor element has linearity with respect to the temperature, thetemperature is calculated by a simple computation. However, actually,the temperature range in which the relation between the temperature andthe temperature sensor element output has linearity is limited, andnon-linearity results in the range of operating temperature of the shiftcontroller. Calculation of temperature by concrete methods as mentionedbelow is contemplated. First, as one method, there is described a methodfor linear approximating B variable of a thermister to calculatetemperatures. Generally, the B constant of a thermister is of anon-linear type with respect to an output (v_(temp)) of the temperaturesensor element, which is linear approximated by the minimum squaremethod.v _(i mid):=(v _(i max) +v _(i min))/2{i=1,2   (5)

The B variable (:=B′) in the linear form is substituted for Expression 6described below to thereby calculate a temperature.B′:=60.6/2¹⁰×5·V _(temp)+3198.2   (6)

Wherein R:=5600, Ro:=10000, Vcc: 1023 (5 v), and To:=25+273.

However, it is necessary for carrying out computation of logarithmcontained in the numeral 6 directly by a microcomputer to carry out32-bit arithmetic calculation such as floating decimal point. Since thisarithmetic calculation takes time for computation, log terms inExpression 6 are broken up, as in Expression 7, and further Maclaurin'sseries is expanded to thereby shorten the computation time.$\begin{matrix}{t:=\left\{ {{\frac{1}{B^{\prime}} \cdot {\log_{e}\left\lbrack {\frac{R}{R_{0}}\left( {\frac{V_{CC}}{V_{temp}} - 1} \right)} \right\rbrack}} + \frac{1}{T_{0}}} \right\}} & (7) \\\begin{matrix}{{\log_{e}(X)} = {\log_{e}\left( \frac{2^{n} \cdot X}{2^{n}} \right)}} \\{= {{\log_{e}\left( 2^{n} \right)} + {\log_{e}\left( \frac{X}{2^{n}} \right)}}} \\{= {{n \cdot {\log_{e}(2)}} + {\log_{e}\left( \frac{X}{2^{n}} \right)}}}\end{matrix} & (8)\end{matrix}$

Further, the second method is a table method. In this method, acorresponding table of the actual temperature and the temperature sensorelement output is prepared in advance, and the present temperaturesensor element output and this corresponding table are used, and atemperature is calculated by a linear complement or a tertiarycomplement.

Further, the third method is an approximation method by way of atertiary function. In this method, the actual temperature and thetemperature sensor element output are approximated by a tertiaryfunction, and its constant is stored or recorded. When a temperature iscalculated, the temperature is calculated using the output of thetemperature sensor element and the coefficient of the tertiary function.Further, where a temperature is desired to be obtained with highaccuracy, the region is divided into some regions by the temperaturesensor element output, and the actual temperature and the temperaturesensor element output are approximated by the tertiary function everyregion, which coefficient is stored or recorded. When a temperature iscalculated, the region is discriminated by the output of the temperaturesensor element, and further, the temperature is calculated using thecoefficient of the tertiary in that region and the output of thetemperature sensor element (see Expression 9). In the presentembodiment, the latter method is employed. $\begin{matrix}{{\log_{e}\left( \frac{X}{2^{n}} \right)} = {{\sum\limits_{i = 1}^{\infty}{\left\{ {\left( {- 1} \right)^{i - 1} \cdot \frac{1}{i} \cdot \left( {\frac{X}{2^{n}} - 1} \right)^{i}} \right\}{\log_{e}(2)}}} = 0.693}} & (9)\end{matrix}$

Concretely, as shown in FIG. 18, the temperature sensor element outputis divided into three regions according to the temperature sensorelement output. The region dividing conditions and the coefficients{α·β·γ·σ} of the tertiary function approximated in the respectiveregions are given in Table 3. TABLE 3 COEFFICIENT REGION CONDITIONS α βγ δ I 0.7 <= vn 8.68E + 02 1.96E + 03 1.56E + 03 4.29E + 02 II −0.7 <=vn < 0.7 1.96E + 01 4.94E + 00 5.00E + 01 3.77E + 01 III vn < −0.75.84E + 02 −1.27E + 03   1.03E + 03 −2.17E + 02  

Here, v_(tn) is a value normalized so that the maximum value is 1 andthe minimum value is −1 of the temperature sensor element output.

<Computation of Rotation Angle>

FIG. 19 shows the process for calculating the rotation angle from theoutput of the sensor element 3. Signals of two systems corresponding tothe rotation angle of the magnet are output through the amplifier fromthe non-contact sensor while being affected by the magnetic circuitaround the magnet irrespective whether or not the motor is driven. Noisecomponents such as a periodical noise generated form the motor aresometimes included in the output signal of the amplifier, and where thenoise components cannot be ignored, it is necessary to remove the noisecomponents. In the present embodiment, a lowpass filter is provided onthe output stage of the amplifier in order to remove the noises. Asignal having passed through the lowpass filter is input into a computersuch as the microcomputer 4. Therefore, it is necessary that a computeror an electronic circuit be provided with an analog input function.Further, a higher-order filter can be provided even within the computer.This is generally called a digital filter such as FIR or IIR, and thenoise components can be removed more effectively. In the presentembodiment, there is used a lowpass filter (cutoff frequency; 1 kHz) onthe circuit board comprising a resistor (10 kΩ) and a condenser (0.1μF). Further, an output of the temperature sensor element is input intoa computer such as the microcomputer 4 (104), and a region is decided bythe value of the temperature sensor (105). A temperature is calculatedusing the coefficient in each region calculated previously (106). In thecomputer such as the microcomputer 4, an output mean value of the sensorelement 3 is compensated for the temperature characteristic from thesignal from which noise was removed and the calculated temperature(107). Next, the output amplitude of the sensor element 3 is compensatedfor the temperature characteristic thereof using the signal for whichthe temperature characteristic of the output mean value of the sensorelement 3 is compensated for and the calculated temperature (108).Further, the signal for which temperature is compensated for isnormalized (109), and a region is discriminated using the conditionsgiven in Table 2 (110). Since the coefficients of the tertiary functioncalculated every region at the time of calibration are stored in EEPROM,the rotation angle is calculated on the basis of Expression 9 using onevalue that should be used for computation out of the coefficients andthe signals normalized of two systems (111).t=α·v _(tn) ³ +β·v _(tn) ² +X·v _(tn)+δ  (10)

Wherein θ indicates the calculated rotation angle, {a, b, c, d}indicates one belonging to the selected region out of the coefficientsof the tertiary function calculated by calibration, and v indicates onevalue that should be used for computation out of the normalized signalsof two systems. From the foregoing, the detection of the rotation angleof the rotating shaft 11 becomes enabled over the whole region in therange of operating temperatures and over the whole region of rotationangle (360 degrees).

<Control of Motor>

Next, a method for causing the output shaft to follow the targetrotation angle will be mentioned. In the microcomputer 4 arranged on thecircuit board 2, a torque command value given to the motor is calculatedfrom the calculated present shaft rotation angle (111) and targetrotation angle information (112) obtained from a mode selection signal.Various calculation methods are adopted for this calculation. In thefollowing, there is defined that an angle increases in the rightdirection of rotation. For example, in a first method, the torquecommand value given to the motor has three types, i.e., constant on thepositive side, zero, and constant on the negative sides. In this case,where the shaft rotation angle is smaller than the target rotationangle, the motor is rotated in the right direction at a determined Dutyratio, or where the shaft rotation angle is larger than the targetrotation angle, the motor is rotated in the left direction at adetermined Duty ratio. Then, when registered or reached near, torque isset to zero. In this method, however, where inertia of the motor or theoutput shaft is not sufficiently large, even if the torque given to themotor is set to zero, the phenomenon that the motor continues to operatewith the inertia force occurs probably. As a result, the shaft rotationangle becomes enabled to stop or stand still within the target positiondeviation. In a second method, a deviation between the target shaftrotation angle and the present shaft rotation angle, differentiation oftime and integration up to the time are computed, the weight is appliedand the arithmetic sum is taken to provide the target value of thetorque given to the motor. This is generally called a PID control.However, in the present embodiment, the rotation angle of the shaft iscontrolled, and in such a case, an integrator is included in the controlobject, because of which it is known in the control rule that theintegrator is not necessary. Therefore, in the present embodiment, thePD control is to be employed.

According to the present invention, the constitution described in any ofclaims 1 to 56 is employed whereby any of the following effects could beattained.

No erroneous operation occurs in the control circuit due to the dust,oil or iron powder generated in the gear-receiving chamber.

No erroneous operation occurs in the rotation angle sensor or the signalprocessing circuit due to the dust, oil or iron powder generated in thegear-receiving chamber.

The constitution of the sensor mechanism for detecting the rotatingposition of 360 degrees of the output rotating shaft is simplified.

The resolution of the sensor is not affected by the gear ratio.

Since the sensor output signal is an analog signal, the continuous angledetection becomes enabled.

The distance between the rotational body and the sensor element can bemade not less than 3 mm, and management of the distance between therotational body and the sensor element becomes easy.

The generated magnetic flux of the magnet is effectively utilized, andno attenuation of magnetic flux occurs, because of which an inexpensivemagnet can be used, and assembling becomes simple.

Since application of milling cutting for counterbore to the gear coverand the board cover is unnecessary, processing property is improved.

At the time of stalling a motor or at the time of backlash, an excessiveload is not applied to gear portions, and therefore, there is lesspossibility of breaking the gears.

Since a conductor is not used to connect the motor and the circuitboard, there poses no problem of breaking the conductor. Further,workability of connection work is improved.

Since radiation is effectively carried out from the control circuitboard, no problem of erroneous operation of the control circuit occursat high temperatures.

Since no pressure difference between the inside and outside of thecircuit board receiving case comprising a housing and a cover occurs,there occurs no problem of breaking the control circuit board or theboard case.

Since the assembling tolerance is made small, a deviation in apositional relation between the magnet rotational center shaft and thesensor element is reduced, thus reducing a problem that the sensoroutput is different for each product.

The sensor output is unsusceptible to the temperature around the sensorelement, and accordingly, a problem that the resolution is deteriorateddue to the change in temperature is eliminated.

The sensor mechanism is simple.

Since no counterbore need be provided in the gear case (housing) and theboard case (cover), no problem that the distance between gears is varieddue to the assembling tolerance or processing tolerance occurs.

While the invention has been described in its preferred embodiments, itis to be understood that the words which have been used are words ofdescription rather than limitation and that changes within the purviewof the appended claims may be made without departing from the true scopeand spirit of the invention in its broader aspects.

1. A non-contact magnetometric rotation angle sensor comprising: amagnet mounted on a rotational body; an MR element positioned within amagnetism distribution space of a magnet and reactive in a direction ofa magnetic field; and a circuit board having a signal processing circuitfor approximating an output signal of the MR element every specificregion with respect to a rotation angle of the rotational body with amulti-function, uniting dividing regions and outputting a signallinearized over 360 degrees, wherein a nonvolatile memory is mounted onsaid circuit board for storing a constant obtained by calculation withsaid circuit.
 2. The sensor according to claim 1, wherein the MR elementis a GMT element which is reactive in the magnetic field direction. 3.The sensor according to claim 1, wherein the sensor is configured tocalculate the multi-function by calibration.
 4. The sensor according toclaim 1, further comprising a non-magnetic holding plate for the circuitboard.
 5. The sensor according to claim 1, wherein a yoke member made ofmagnetic material is arranged at a position in contact with the magnetand at a position opposite to the MR element.
 6. The sensor according toclaim 1, wherein the sensor is configured to function such that theoutput signal of the MR element and an output signal of a temperaturesensor arranged on the signal processing circuit board are processed bythe circuit, and the output signal of the MR element is compensated fora temperature characteristic thereof.
 7. The sensor according to claim1, wherein a non-magnetic body is arranged to isolate the rotationalbody and the MR element.